Cudagraphs support for compiled optimizers (#107504)
Marks all params/optimizer state as static addresses and a finalizer which cleans up the graph attributes when the optimizer goes out of scope.
**Note: this does not mark grads as static because this will increase memory usage significantly
There are two cases:
1. The upstream graph is cudagraphed - this case will work fine OOTB
2. The upstream graph is not cudagraphed - in this case, there will be a lot of copies introduced from the upstream (to copy the grads) into cudagraphed-owned memory, unless the user explicitly marks the grads as static. If the user does this, this will also require not deallocating the grads in zero_grad() (either the mod or optimizer version) by setting them to zero vs None. There is a PR (https://github.com/pytorch/pytorch/pull/107853) in flight to throw an error if zero_grad attempts to set static grads to None.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/107504
Approved by: https://github.com/eellison
